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Topic: Davis anemometer failing already? (Read 2476 times)

Hi folks, please see the video below, does it look like my anemometer is failing already?This has happened a few times now, its like it sticks for a while, but once it wakes upit actually works very well at low speeds, better than the OS of course, but as you can see from the video, it should have been spinning long before now....

Please excuse one of the boys deciding to have drink at the same time....

I only had it down a couple of days ago to sort out the wiring to the shield and move the OS solar. I gave it the once over and there was nothing untoward, watching the live video now, it seems okhttps://youtu.be/ZuRBCAGyLCQ Go to 35:40 and you can see the Davis playing properly, very strange, could it have been dew?

This time of year, I have to physically break the restraining spider webs EVERY DAY! You can't necessarily see the web strands but once you "turn" the anemometer cups with a LONG stick (26' in my case) everything is good until overnight when it starts again.

Thanks guys, i am going to rule out improper installation due to the fact that it can be 100% ok at low speeds at timesincluding 1mph, i think this was seen in the last video (live one) i posted, I have some decent binoculars and a a canon 70D with a 16-300mm lens, i have used both and cannot see anything untoward up there, bear in mind thiswas all down only a couple of days ago and i could see nothing visually wrong, i always give it all a once over even ifi have brought the mast down to work on something else.

Tech at McMurdo has seen the video and is suggesting that the bearing is looking like its on its way out, the rocking when stopped is the give away there.... I have already emailed back their RMA form....

Had another convo with McMurdo this morning, they said it could take up to 5 days before the sendanother out after they have received mine, that wasnt acceptable to me, could be around 10 dayswithout an anny no, no, no, I asked Sharon if it would be possible to send the replacement1st, then i can swap it out and send mine back, that way the mast will have to come down just the onceThankfully she agreed and should hopefully have one by Tuesday, from what i gather though, my annyis an older model that they do not have any more

I've just had this problem on my VP2 anemometer. One of the bearings had deteriorated and was preventing the shaft from spinning under light wind pressure. I fixed it myself - on the version I have (the non-reed version with the brass tip on the vane) it's a very easy repair.

Drop the anemometer (mine is on a 5m pole), remove the cups, remove the crosshead screw holding the anemometer to the vane and pull it away. In a clean area, remove the E clip holding the shaft in place and drop the shaft and magnet out of the housing. Use a screwdriver or thin rod to loosen and remove the two bearings, clean any dirt out and push the new ones into the housing. Clean the anemometer shaft and pass it through the bearings. Refit the E clip, reassemble the vane and anemometer and refit the cups.

I'd imagine the older type is just as easy to repair.

The bearings are type R2ZZ and are available from any decent bearing factor. Buy branded quality replacements (SKF or similar). The old bearings were flanged and the new ones aren't but it makes no difference to the unit's operation at all.

Yes, clean out the housing and clean the anemometer shaft. The type of bearing used in the anemometer is sealed for life and is simply replaced as a unit when necessary. Quality bearing brands include SKF, FAG, Toyo and Timken but a reputable bearing factor will only supply quality manufacturer items.

It's sounds like you may have either spiderwebs restricting the cup movement or you may have a bad wind speed bearing. It is quite common to see poor low speed readings or readings that appear to be stuck.

Would pay to take your anemometer down and inspect it. If in doubt change the bearing there not terribly dear. Then ensure your Allen key screw is well secured again.

remove the E clip holding the shaft in place and drop the shaft and magnet out of the housing.

How exactly do you get the bearings out of the housing? I've removed the E clip, shaft and magnet, but can't see how it comes apart any further. Do you need a lot of force to loosen the bearings?

It doesn't need a lot of force after all the housing is only plastic. The way I got mine out was with a thin shaft screwdriver. I put the shaft through the centre of the bearing and rocked it gently to break it away then just pulled it out.

what are those spikes on your anemometer. I don't think they are causing the problem. I have one that has stopped moving, and then starts up when a good blast of wind. i am using a lower unit but the top one has me baffled . It could be crud up inside the unit causing it to stick. and a simple clean out works. Also balance of the unit on the mast, although that is along shot. let us know what you find. What I would do, is put up your new unit. then if this unit is fixable, mount it lower on your mast a bit as a back up , carefully tie the wires not to pinch them and then put a baggie on the R plug as a backup. OR you can do as I did invest in a wireless Anemomenter. then when one goes tits up, I can just select the station for the wind from my computer.

It doesn't need a lot of force after all the housing is only plastic. The way I got mine out was with a thin shaft screwdriver. I put the shaft through the centre of the bearing and rocked it gently to break it away then just pulled it out.

I've managed to get them out. The top one came out much easier than the bottom one which needed excessive force.

Thanks to the excellent WX information on the Davis Vantage Pro anemometer, I have been able to repair the original ‘Mk 1’ anemometer that my son (whose weather station it is) had to discard 3 years ago when it stopped working. He had to replace it with the later Mk. 2 version (with a detachable anemometer cup spindle unit), since the Mk. 1 was no-longer available, but this replacement anemometer has now also stopped working. Now, however, thanks to the information sheets, he can replace it with the repaired Mk. 1 unit.

Some comments on your Mk. 1 Davis VP information sheets

In the UK, both the anemometer is fitted with a 4-wire, flat ASDL2 cable with an RJ11 (4-pin) plug, though wired just as the information sheets show. A 6-pin plug is not used.

Although the anemometer unit cannot be taken apart easily, the direction potentiometer can be prized out fairly easily after cutting out the 4 ‘stakes’ round the edge of the plastic disk it’s mounted on. I think they’re made by melting the plastic locally with a hot punch, but the joints so formed can be detached with a sharp-pointed knife. The black and red wires from the reed switch are just long enough to allow the potentiometer to slide right out. But before you try to do this, the cable must be released so that it can slide freely through the mounting tube (by removing the flattened tubular plug/cable clamp at the bottom end of the tube - use a wood screw screwed into the plug to remove it). When replacing this cable plug, make sure the flattened part is parallel to the clamp screw that goes through the tube so that it holds the cable well away from the screw thread.

Neither the Bourns 6639 potentiometer listed as a spare (nor its Vishay 357B0203MAB251S22 equivalent) have the extra ‘spare’ terminal for the black wire, but one can be stuck on with epoxy to provide a support if necessary. The genuine Davis potentiometer is clearly a ‘special’. If you do need to replace the potentiometer, however, the potting compound round the 4 terminals on it is soft and easily cut off. In the UK, both replacement potentiometers are off-the-shelf from RS Components.

Mk. 2 version

My son’s Mk. 2 anemometer has developed an unusual fault. The wind-speed indicator works perfectly, as does the wind vane - in all compass directions except W, when it continuously indicates N. I think this can only be a potentiometer fault - presumably, for some reason, the slider isn’t making contact with the track in that position - possibly a speck of dirt - so, (in spite of the 909 ohm resistor?) the green wire ‘sees’ 0V, indicating N. I’m hoping the circuit is basically similar to that of the Mk. 1 unit, so that this logic works!

Does anyone have any other explanation for this behaviour or more information about the Mk. 2 anemometer? It would be a great help!

Thanks,

Tony Pennell.

Incidentally, the bearings on the anemometer cup spindle are much easier to replace on the Mk. 2 version! As with the Mk. 1 version, replace both ball bearings. SKF is good!

.... with an RJ11 (4-pin) plug, though wired just as the information sheets show. A 6-pin plug is not used.

Technically, RJxx refers to the wiring of the jack, and RJ11 (if referring to the connecting plug) would have 6 positions but only 2 wires. RJ14 would be what you are describing (technically). But that's a really pedantic point.